National's finance spokesperson Amy Adams spoke to media about her new role on Wednesday. Credits: Newshub

National's new finance spokesperson Amy Adams has adopted her predecessor's claim that the Government has a fiscal hole, saying it could be "considerably more".

The $11.7 billion fiscal hole claim was made by Steven Joyce during the election campaign, and was debunked by economists at the time.

"I wouldn't be surprised if the gap ends up being considerably more than that if you look at what they'd be required to spend to fund demographic pressures, cost pressures and their very expensive commitments that they've made through the campaign in the Speech from the Throne and since," Ms Adams said in a media standup on Wednesday afternoon.

Finance Minister Grant Robertson said "It's not a great start for Amy Adams to keep digging Steven Joyce's discredited hole."

Ms Adams couldn't name an exact figure, saying there will be a "very large" difference in what the Government promised and what it can afford.

"Exactly what it is, we'll know more when the Government puts out their numbers."

Asked about the hole a second time, Ms Adams would not say Mr Joyce's figure was wrong.

"The number I'm interested in is the gap now between what Labour is promising, what they've committed to and what they're able to deliver."

She said there will be a shortfall, which can only be met by new taxes or higher debt.

Mr Robertson told Newshub in response to her claims: "The Treasury has said at their half year update before Christmas that we are on track to meet our Budget Responsibility Rules.

"Our allowances for new spending in the Budget are in fact larger than what the previous government set aside and will support our ambitious programme. We will have to work hard to make up for the social and infrastructure deficits left by the previous government but we are getting on with the job".

Ms Adams says her experience across a number of Ministerial portfolios will help her in taking up her new role.

"My work in both the finance area and infrastructure area, in the social policy areas, in justice and environment give me an excellent understanding across Government."

She worked as Associate Finance Minister under Steven Joyce to prepare the 2017 Budget, and chaired the Finance and Expenditure Committee in her first term in Parliament.

Before Parliament she was a partner at Mortlock McCormack Law in Christchurch, specialising in commercial law.

During the campaign for the National leadership, she and fellow contender Simon Bridges promised each other a significant role should one of them become leader.

"He's a person I like and admire and respect and I think equally that I'm a person he admires and respects," she said.